classbound-package: classbound: Visualization for Classification Decision...

In classbound: Visualization for Classification Decision Boundaries

classbound: Visualization for Classification Decision Boundaries

Description

The classbound package provides tools for exploring, visualizing, and comparing classification decision boundaries in R. It supports both two-dimensional data and high-dimensional data (via 2D slicing or linear projections), and works with native R classifiers, tidymodels workflows, and user-supplied models.

Details

Two main workflows

Interactive workflow: Launch explorapp() to start the built-in Shiny application. From there, you can import your own data, simulate datasets, draw data by hand, choose classifiers, adjust parameters, compare decision boundaries side-by-side, inspect probability surfaces, inject outliers, and export the results.

Programmatic workflow: Use the modular API directly:

model <- fit_model(data, formula, classifier)
model <- boundary_compute(model, feature_range, resolution = 100)
plot_boundary(model, obs_data = data, x_col = "x", y_col = "y", true_label = "class")

For a one-step wrapper, use classbound().

High-dimensional data

When a model is trained on more than two features, boundary_compute() supports two visualization strategies:

• 2D Slice: two features are selected for the axes; all other numeric features are fixed at their median and categorical features at their mode.

• Projection: a projection matrix maps the high-dimensional feature space to two dimensions (e.g., PCA or a tour basis from the tourr package). The boundary grid is generated in projection space and inverse-projected back for prediction.

Supported classifiers

Any classifier whose predict() method returns a vector or factor of class labels works automatically. Built-in adapters are provided for rpart, randomForest, PPtreeViz, PPtreeExt, and ppforest2. For classifiers that return complex objects (such as lists), use the predfun argument to extract class labels. Native tidymodels integration is available via boundary_workflow_set().

Author(s)

Maintainer: Vaibhav Manihar [e-mail]

Authors:

• Vaibhav Manihar [e-mail]

• Natalia da Silva [e-mail] (ORCID)

• Ignacio Alvarez-Castro [e-mail] (ORCID)

See Also

• classbound() for the all-in-one wrapper

• fit_model() to fit a model

• boundary_compute() to compute a decision boundary

• plot_boundary() to visualize a decision boundary

• explorapp() for the interactive Shiny application

• boundary_workflow_set() for tidymodels multi-model comparison

classbound documentation built on Sept. 30, 2026, 5:13 p.m.